Vertebral implants are often used in the surgical treatment of spinal disorders such as degenerative disc disease, disc herniations, curvature abnormalities, and trauma. Many different types of treatments are used. In some cases, spinal fusion is indicated to inhibit relative motion between vertebral bodies. Motion between vertebral bodies is naturally provided in part by the flexible disc material that resides between adjacent vertebral bodies. Spinal fusion often involves the removal of the vertebral disc and insertion of an interbody implant to create a fused junction between a pair of vertebral bodies. Fusion may also occur at multiple vertebral levels or between vertebral bodies that are several levels apart. Interbody implants may be coated, filled, or surrounded by growth promoting materials such as BMP, DBM, allograft, autograft or other osteoinductive growth factors to facilitate fusion between the vertebral bodies and the implant.
Conventionally, interbody implants are inserted into the space between vertebral bodies after the disc material has been removed and after the vertebral end plates are prepared. This end plate preparation may include shaping, planing, scraping, or other decorticating processes in which bone matter is removed and blood flow is initiated to enhance bone growth into the interbody implant. Ideally, new bone matter forms and bridges the gap between the vertebral bodies and the growth promoting material. In certain instances, particularly where the growth promoting material is contained within the interbody implant, new bone matter does not sufficiently span the gap between the vertebral endplate and the growth promoting material. Consequently, the fusion site may be compromised.